Title :
Refinement of Nd-422 particles in Nd-Ba-Cu-O bulk superconductor
Author :
Iida, K. ; Yoshioka, J. ; Murakami, M.
Author_Institution :
Superconductivity Res. Lab., Int. Superconductivity Technol. Center, Iwate, Japan
fDate :
3/1/2001 12:00:00 AM
Abstract :
We have investigated the effect of oxygen partial pressure, the initial composition, and the addition of CeO2 and/or Pt on the grain growth of Nd4Ba2Cu2O10 (Nd-422) in the Ba-Cu-O liquid. Logarithmic plots of the mean diameter of Nd-422 under various oxygen levels as a function of the holding time showed the power law behavior with the slope of 1/3, which suggested that the grain growth of Nd-422 could be explained in terms of the Ostwald ripening theory. A reduction of oxygen partial pressure, the shift of the initial composition toward Ba-rich direction, and a combined addition of Pt and CeO2 could suppress the coarsening of Nd-422. Furthermore, a combination of these techniques was found to be effective in refining the Nd-422 in the Nd-123 matrix, which led to an enhancement of Jc values
Keywords :
barium compounds; cerium compounds; critical current density (superconductivity); grain growth; grain refinement; high-temperature superconductors; neodymium compounds; platinum; stoichiometry; Ba-Cu-O liquid; CeO2; Jc; Nd-422 particles; Nd-Ba-Cu-O bulk superconductor; Nd4Ba2Cu2O10; NdBa2Cu3O7:CeO2,Pt; Ostwald ripening; Pt; composition; diameter; grain growth; holding time; logarithmic plots; oxygen partial pressure; power law behavior; refinement; Crystal microstructure; Furnaces; Laboratories; Magnetic materials; Powders; Superconducting magnets; Superconducting materials; Superconductivity; Telephony; Temperature;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
